. they are mostly usedinenvironmentsfortheenvironment, whetherit be the sand in the desert or the jungle, it would interfere with the explosive. that has been traditionally their use. that being said, these things are easy to find, easy to make. i don't have to tell you, you can look up on the internet and see the step by step instructions out to do that. and matter of assembling the various ingredients you would do to put it together. that to expand on what he was saying, they are getting a lot of evidence how the bomb was made but they don't have a lot of evidence about who did this or why. the actual evidence that would lead to the person or persons involved. >> this suggests a slightly higher level of them what was first thought yesterday and if so, does that narrow down the net of potential suspects? >> it does. the black powder, the acetone, peroxide, you don't want to let it get went. absolutely right. you want to protect the explosives, the detonator. when this bomb went off, talked to a couple of people and their first reaction was what is happening to people coming back from af

with it in such a reallyhorrificenvironment. andpeople were able to do the things they had to do quickly, efficiently, it was really the most collaborative team effort that i have ever seen. i've been doing this now for over 20 years. i get involved in a number of other situations or events. really not to this extent. certainly not to the degree that we saw, with this one. but this is one that brought everybody to the table. and it was a remarkable effort from the people who dealt with the patients in the field to the ones who dealt with them in the hospital. it's difficult emotionally, when you're dealing with a very, very injured, young, young child. it raises more feelings, but i think the key is to be able to do what you do. and do it as quickly as you can. >> you've done an extraordinary job. you and your staff i want to thank you for your service, on behalf of everyone from around the world. i'm sure your actions saved a lot of lives. for that we're all incredibly grateful. thank you. >> thank you very much. >>> we'll be right back. zap technology. arrival. with hertz gold plus rewards, you ski

oftheenvironmentthatwere involved in the blast. >> reporter: that same trauma surgeon saying some of the patients have to come back again and again for repeat operations. also saying that he has never seen anything, john, like the volume, the quantity of people that were rushed into his er immediately following this attack. >> that's what we keep hearing, poppy. the numbers were just staggering. so how prepared were they really for this flood of victims? >> reporter: you can say fortunately they were prepared. fortunately for a situation as they wished would never happen because they told us they prepare for things like this, massachusetts general, saying that within minutes after they got their first patient and after the attack they instituted an incident command system within five to ten minutes. they had enough surgeons. they even told us they had people flying back in, coming within hours back to the hospital from trips to try to help and do everything that they could. but they were prepared and they do have the hands needed at this point in time, john. >> you know, poppy, i did. i heard fro

the situation. the safety of everyone that ntue to dovethgo wils always ensure asafeenvironmentforour fans." this notion ofpoing events, like the boston marathon, which hasad us loong at other viously, we have tonn marathon on sunday, officials there is a that they are paying close attention to their security preparations, we have also got some other races, i chke john. n ancisco marathon in ju, billy broadtreet run in may, indiana 500 festiva in may. lansing, michigan, in april, and raon inapl.cnt music obvisl ainwee talking about no credie threats, but officials in boston said no credible threats before tha o either, john. >>recautions are necesry important, and detandable the celticsamn boston, canceled. doesn't really matter. the playoffs just around the corner. that game will not be made up. shannon travis, our thanks to you. one other story about a sporting event which reallyauty attention overnight. fans of the oakland a's in oakland, tryg to rally fans to start instead of let's go a's chant, a let's go bostonchant. that just shows you how fans and right now.he city country are repu

whether this came fromtheenvironment, right?but it is not. >> i can tell you, as a person who has done trauma surgery, it can be difficult to tell sometimes when you're actually taking some of the shrapnel, wear exactly did it come from. but now they're saying without a doubt, we asked a few times, that there were nails, carpenter nails specifically and, quote, bb-like metal within some of these patients. and so they -- they know for sure it came from the explosive device. this is a doctor saying that based on their medical examination. this wasn't just debris that was lying around. >> what about also quickly in terms of the amputations, i was hearing one of the doctors saying last night, some of the patients were coming to them very injured, bleeding and saying, take whatever you need, i want to be alive. that has to be tough for a doctor, though. >> these are i think heart breaking decisions. it is a -- you can make the decision fairly quickly if that's going to be the best course of action. >> life or death. >> if you don't do the amputation, sometimes it can mean infection, that ca

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